Method and system for providing a virtual space

ABSTRACT

A method including defining a virtual space for immersing a user. The method further includes defining a field of view of a head mounted display. The method further includes generating an image of the field of view based on the virtual space that is visually recognizable by the user. The method further includes updating the image of the field of view in synchronization with movement of the head mounted display. The method further includes generating the image of the field of view including a guiding region which covers a part of the virtual space for guiding a sight line of the user when the image of the field of view is updated without synchronization with the movement of the head mounted display. The method further includes displaying the image of the field of view on the head mounted display.

RELATED APPLICATIONS

The present application claims priority to Japanese Application Number2016-019777, filed Feb. 4, 2016, the disclosure of which is herebyincorporated by reference herein in its entirety.

BACKGROUND

This disclosure relates to a method and system for providing, to a headmounted display, a virtual space in which a user is immersed.

In Japanese Patent No. 5,767,386, the following head mounted displaysystem is disclosed. While an application is running, the head mounteddisplay system performs processing of changing display of an image in avirtual space, which is displayed in a user's visual field insynchronization with movement of a head of a user wearing a head mounteddisplay (hereinafter also referred to as “HMD”). Meanwhile, the displayof the image in the virtual space can be changed with use of acontroller that is connected to the HMD so as to be capable ofcommunicating to/from the HMD.

In the head mounted display system as disclosed in Japanese Patent No.5,767,386, when a visual-field image that is visually recognized by theuser is updated by changing a position and a direction of a virtualcamera that defines the virtual space image of the field of view. Asdisclosed in “[CEDEC 2015] What should be ‘avoided’ in VR? Oculus VRteaches a technique for comfort VR content production,” [online], Aug.22, 2015, 4Gamer.net, [search on Jan. 13, 2016], Internet <URL:http://www.4gamer.net/games/195/G019528/20150828092/>, when the virtualcamera is moved backward, moved at high speed, or moved in a curvedmotion, the user is more susceptible to the VR sickness.

SUMMARY

This disclosure includes a method and system for providing a virtualspace, which are capable of reducing VR sickness without reducing auser's sense of immersion to a virtual space.

According to at least one embodiment of this disclosure, there isprovided a method of providing, to a head mounted display of anon-transmissive type (or partially transmissive), a virtual space inwhich a user is immersed. The method includes generating a visual-fieldimage that is visually recognizable by the user in a virtual space imageforming the virtual space. The method further includes updating theimage of the field of view in synchronization with movement of the headmounted display. The method further includes generating, when the imageof the field of view is updated without synchronization with themovement of the head mounted display, a sight line guiding region forguiding a sight line of the user, and displaying the sight line guidingregion and the image of the field of view on the head mounted displaysuch that the sight line guiding region covers a part of the image ofthe field of view.

Further, according to at least one embodiment of this disclosure, thereis provided a system for causing a computer to execute the method ofproviding the virtual space described above.

According to this disclosure providing the virtual space, which iscapable of reducing VR sickness without reducing the user's sense ofimmersion to the virtual space is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a configuration of an HMD system accordingto at least one embodiment of this disclosure.

FIG. 2 is a block diagram of a hardware configuration of a controlcircuit unit included in the HMD system of FIG. 1.

FIG. 3 is a diagram of an orthogonal coordinate system on athree-dimensional space defined about a head of a user wearing an HMD.

FIG. 4A is a YZ plane diagram of at least one example of a virtual spaceand a virtual camera.

FIG. 4B is an XZ plane diagram of at least one example of the virtualspace and the virtual camera.

FIG. 5 is a diagram of at least one example of the movement of thevirtual camera when a visual-field image is updated withoutsynchronization with the movement of the HMD.

FIG. 6 is a diagram of at least one example of the movement of thevirtual camera when the image of the field of view is updated withoutsynchronization with the movement of the HMD.

FIG. 7 is a block diagram of the function of the control circuit unit,for achieving the configuration of at least one embodiment.

FIG. 8 is a flow chart of a method of processing in the HMD systemaccording to at least one embodiment.

FIG. 9 is a diagram of a display example of a sight line guiding regionto be displayed on the HMD according to at least one embodiment.

FIG. 10 is a diagram of an additional configuration of the sight lineguiding region illustrated in FIG. 9.

FIG. 11A, FIG. 11B, and FIG. 11C are diagrams of a display example of asight line guiding region to be displayed on an HMD according to atleast one example.

FIG. 12 is a diagram of an additional configuration of the sight lineguiding region according to the at least one example shown in FIG. 11Ato FIG. 11C.

DETAILED DESCRIPTION

Contents of at least one embodiment of this disclosure are described andinclude a method and a system for providing a virtual space according toat least one embodiment of this disclosure have the followingconfigurations.

(Item 1)

A method of providing a virtual space according to an embodiment is amethod of providing, to a head mounted display of a non-transmissivetype, a virtual space in which a user is immersed. The method includesgenerating a visual-field image that is visually recognizable by theuser in a virtual space image forming the virtual space. The methodfurther includes updating the image of the field of view insynchronization with movement of the head mounted display. The methodfurther includes generating, when the image of the field of view isupdated without synchronization with the movement of the head mounteddisplay, a sight line guiding region for guiding a sight line of theuser, and displaying the sight line guiding region and the image of thefield of view on the head mounted display such that the sight lineguiding region covers a part of the image of the field of view.

With this configuration, when the image of the field of view is updatedwith use of, for example, an external controller or through specificscene change without synchronization with the movement of the headmounted display, the sight line guiding region for guiding the sightline of the user is displayed. Therefore, an amount of information thatenters the brain of the user is reduced. With this, VR sickness of theuser is reduced in some instances. Further, while the image of the fieldof view is displayed, the sight line guiding region is displayed so asto overlap with a part of the image of the field of view. Therefore, theuser's sense of immersion to the virtual space is maintained.

(Item 2)

In at least one embodiment, the updating the image of the field of viewis carried out by changing a position and/or a direction of a virtualcamera defining the image of the field of view.

Examples of the update of the image of the field of view includechanging the direction of the virtual camera without moving the positionthereof, moving the position of the virtual camera without changing thedirection thereof, and moving the position of the virtual camera whilechanging the direction thereof.

(Item 3)

In at least one embodiment, the sight line guiding region is displayedso as to cover a half or more of the image of the field of view.

With this configuration, the visual effect of guiding the sight line ofthe user can be sufficiently obtained, and the VR sickness can bereliably prevented.

(Item 4)

In at least one embodiment, the sight line guiding region is generatedin a size extending to an outer side of a region of the image of thefield of view in the virtual space.

Assuming a case where the image of the field of view is updated bychanging the direction of the virtual camera in synchronization with themovement of the head mounted display, as in the above-mentionedconfiguration, in at least one embodiment, the sight line guiding regionis extended to the outside of the region of the image of the field ofview.

(Item 5)

In at least one embodiment, the sight line guiding region includes asight line concentrating object on which the sight line of the user isfocused.

In at least one embodiment, the sight line concentrating object isconfigured to give, to the user, such a visual effect that the user ismoved in the virtual space in a direction of change of the positionand/or the direction of the virtual camera.

With this configuration, the sight line concentrating object can providesuch a visual effect that the user himself/herself feels like beingmoved in a predetermined direction, and hence the predictability of theuser is enhanced to cause less VR sickness.

(Item 6)

In at least one embodiment, arranging the sight line concentratingobject also outside of a region of the image of the field of view in thevirtual space.

Assuming a case where the image of the field of view is updated bychanging the direction of the virtual camera in synchronization with themovement of the head mounted display, as in the above-mentionedconfiguration, in at least one embodiment, the sight line concentratingobject is arranged also outside of the region of the image of the fieldof view.

(Item 7)

A system according to at least one embodiment is a system for causing acomputer to execute the method of any one of Items 1 to 6.

With this configuration, providing the system capable of reducing VRsickness without reducing the user's sense of immersion to the virtualspace provided on the head mounted display is possible.

Some examples of a method of providing a virtual space to an HMD and aprogram for causing a computer to execute the method according to atleast one embodiment of this disclosure are described below withreference to the drawings. The virtual space is herein athree-dimensional virtual space, but this disclosure is not necessarilylimited thereto. This disclosure is not limited to those examples, andis defined by the scope of claims. This disclosure is intended toinclude all modifications within the scope of claims and the equivalentsthereof. In the following description, like elements are denoted by likereference symbols in the description of the drawings, and redundantdescription thereof is omitted.

FIG. 1 is a schematic view of a configuration of an HMD system using anHMD according to at least one embodiment. FIG. 2 is a block diagram of ahardware configuration of a control circuit unit included in the HMDsystem of FIG. 1.

As illustrated in FIG. 1, an HMD system 100 includes an HMD 110 that iswearable on a head of a user U, a control circuit unit 120, a movementsensor 130, and an external controller 140.

The HMD 110 includes a display unit 112, an HMD sensor 114, andheadphones 116. In at least one embodiment, the headphones 116 are notincluded in the HMD 110, and a speaker and headphones that areindependent of the HMD 110 are usable.

The display unit 112 includes a non-transmissive, or partiallytransmissive, display device configured to completely cover a field ofview (visual field) of the user U wearing the HMD 110. With this, theuser U is able to see only a screen displayed on the display unit 112.That is, the user U loses the visual field of the external world, andhence the user U is immersed in a virtual space displayed on the displayunit 112 by an application executed by the control circuit unit 120.

The HMD sensor 114 is mounted near the display unit 112 of the HMD 110.The HMD sensor 114 includes at least one of a geomagnetic sensor, anacceleration sensor, or an inclination (angular velocity or gyro)sensor, and is able to detect various movements of the HMD 110 worn onthe head of the user U.

The movement sensor 130 includes, for example, a position trackingcamera (position sensor). The movement sensor 130 is connected to thecontrol circuit unit 120 so as to be capable of communicating to/fromthe control circuit unit 120, and has a function of detectinginformation relating to positions or inclinations of a plurality ofdetection points (not shown) provided on the HMD 110. The detectionpoints are, for example, light emitting portions configured to emitinfrared light or visible light. The position tracking camera serving asthe movement sensor 130 includes an infrared sensor or a plurality ofoptical cameras and detecting the detection points of the HMD 110. Thecontrol circuit unit 120 is configured to acquire information of theposition of the HMD 110 from the movement sensor 130, to therebyaccurately associate a position of a virtual camera in the virtual spacewith the position of the user U wearing the HMD 110 in the real space.

The HMD system includes at least one of the HMD sensor 114 or themovement sensor 130 for detecting the movement of the HMD 110. In atleast one embodiment, when the movement of the HMD 110 is sufficientlydetected with use of any one of the sensors, the other sensor may beomitted.

The control circuit unit 120 is configured as hardware (computers suchas a personal computer and a server computer connected via a network)separable from the HMD 110. In at least one embodiment, the controlcircuit unit 120 is integrated with the HMD 100. As illustrated in FIG.2, the control circuit unit 120 includes a processing circuit 121, amemory 122, a storage medium 123, an input/output interface 124, and acommunication interface 125, which are connected to each other via acommunication bus serving as a data transmission path. In at least oneembodiment, the control circuit unit 120 may be mounted inside the HMD110. Further, in at least one embodiment, only a part of the functionsof the control circuit unit 120 may be mounted on the HMD 110, and theremaining functions may be mounted on hardware different from the HMD110.

The processing circuit 121 includes various processors such as a centralprocessing unit (CPU), a micro-processing unit (MPU), and a graphicsprocessing unit (GPU), and has a function of controlling the entirecontrol circuit unit 120 and HMD system 100.

The memory 122 includes volatile storage devices, such as a read onlymemory (ROM) and a random access memory (RAM), and is configured totemporarily store programs to be used by the processing circuit 121 andcontrol data such as calculation parameters.

The storage medium 123 includes non-volatile storage devices such as aflash memory and a hard disk drive (HDD), and is configured to storeuser authentication programs, game programs including data relating tovarious images and objects, and other programs. The storage medium 123may further construct a database including tables for managing variouskinds of data.

The input/output interface 124 includes various connection terminalssuch as a universal serial bus (USB) terminal, a digital visualinterface (DVI) terminal, and a high-definition multimedia interface(HDMI) (trademark) terminal, and various processing circuits forwireless connection. The input/output interface 124 is configured toconnect the HMD 110, the movement sensor 130, the external controller140, and the like to each other.

The communication interface 125 includes various wire connectionterminals for communicating to/from an external device via a network NW,and various processing circuits for wireless connection. Thecommunication interface 125 is configured to adapt to variouscommunication standards for communication via a local area network (LAN)or the Internet.

The control circuit unit 120 is configured to execute an applicationstored in the memory 122 or the storage medium 123, to thereby present avirtual space on the display unit 112 of the HMD 110. With this, the HMD110 is able to execute an operation for immersing the user U in athree-dimensional virtual space (VR space).

The external controller 140 is a general user terminal, and is, forexample, a game console. In addition, in at least one embodiment, theexternal controller 140 is a portable device including a touch display,e.g., a smart phone, a personal digital assistant (PDA), a tabletcomputer, or a notebook personal computer (PC). The external controller140 includes a central processing unit (CPU), a main storage, anauxiliary storage, a transmitting/receiving unit, a display unit, and aninput unit, which are connected to each other via a bus, in at least oneembodiment. The user U wearing the HMD 110 is able to perform input,e.g., touch operation, to the external controller 140, to thereby givevarious operation instructions to the virtual space.

Next, with reference to FIG. 3, description is given of a method ofacquiring information relating to the position and the inclination(direction of visual axis) of the HMD 110. The information relating tothe position and the inclination of the HMD 110, which is based on themovement of the head of the user U wearing the HMD 110, can be detectedby the movement sensor 130 and/or the HMD sensor 114 mounted on the HMD110. As illustrated in FIG. 3, a three dimensional coordinate system(XYZ coordinates) is defined about the head of the user U wearing theHMD 110. A perpendicular direction in which the user U stands upright isdefined as a Y axis, a direction being orthogonal to the Y axis andconnecting between the user U and the center of the display unit 112 isdefined as a Z axis, and a direction orthogonal to the Y axis and the Zaxis is defined as an X axis. The movement sensor 130 and/or the HMDsensor 114 are/is configured to detect angles about the respective axes(that is, inclination determined by a yaw angle representing rotationabout the Y axis, a pitch angle representing rotation about the X axis,and a roll angle representing rotation about the Z axis), and thecontrol circuit unit 120 is configured to determine angle (inclination)information data for controlling the virtual camera that defines thevisual field information based on the temporal change of the angles.

FIG. 4A is a YZ plane diagram for illustrating an example of a virtualspace and a virtual camera, and FIG. 4B is an XZ plane diagram forillustrating an example of the virtual space and the virtual camera.Further, FIG. 4B is an illustration of a case where the virtual camerais moved in synchronization with the movement of the HMD 110.

As illustrated in FIG. 4A and FIG. 4B, a virtual camera 300 is arrangedinside a virtual space 200. In at least one example, the virtual camera300 is arranged at the center of the virtual space 200. A field of viewregion (visual region of the virtual space 200 that is visuallyrecognizable by the user) is defined based on the position and thedirection of the virtual camera 300 in the virtual space 200. The fieldof view region 201 is determined based on a sight line reference sightline L of the virtual camera 300. The field of view 201 has a firstregion 201A defined as a range including a polar angle α with thereference sight line L being the center in the YZ plane illustrated inFIG. 4A, and a second region 201B defined as a range including anazimuth β with the reference sight line L being the center in the XZplane illustrated in FIG. 4B. An image of the field of view that isvisually recognizable by the user is generated based on the field ofview region 201. The image of the field of view includes twotwo-dimensional images for being recognized by right and left eyesrespectively. The two-dimensional images for the right and left eyes aredisplayed on the display unit 112 of the HMD 110, and thus thetwo-dimensional images are provided to the user as a three-dimensionalimage.

When the movement of the virtual camera 300 is controlled insynchronization with the movement of the HMD 110, the movement of theHMD 110 in the real space is associated with the movement of the virtualcamera 300 in the virtual space 200 such that the sight line referencesight line L of the virtual camera 300 corresponds to the Z-axisdirection (see FIG. 3) of the three-dimensional coordinate system of theHMD 110. For example, as illustrated in FIG. 4B, when the user wearingthe HMD 110 is looking at an object 301 (solid line) arranged in thevirtual space 200, the direction of the virtual camera 300 is set to aposition at which the sight line reference sight line L intersects withthe object 301. For example, when the user moves his/her head such thatthe sight line is directed to the right side as the object 301 is movedto the right side along the horizontal direction in the virtual space,as indicated by the broken line of FIG. 4B, the direction of the virtualcamera 300 is changed to the position at which the reference sight lineL intersects with the object 301′ (broken line) in synchronization withthe movement of the HMD 110, and the field of view region 201 (201B) ischanged as well. When the field of view region 201 is changed, the imageof the field of view that is visually recognizable by the user ischanged as well.

Meanwhile, the field of view region 201 of the virtual camera 300 (thatis, the position and/or the direction of the virtual camera 300) iscontrollable without synchronization with the movement of the HMD 110.For example, the position and/or the direction of the virtual camera 300is changed based on the input to the external controller 140, in someinstances. Further, depending on the content using the virtual space, insome cases, the virtual camera 300 automatically moves in the virtualspace 200 to change the field of view region 201 under a state in whichthere is no movement of the HMD 110 or no input to the externalcontroller 140.

FIG. 5 and FIG. 6 are examples of the movement of the virtual camera ina case where the field of view region of the virtual camera iscontrolled without synchronization with the movement of the HMD.

In FIG. 5, the virtual camera 300 is arranged at a position A anddirected toward the object 301 arranged in the virtual space. In thiscase, when the user performs input for controlling the virtual camera300 to the external controller 140, the virtual camera 300 is movedclockwise to a position B by, for example, being turned about the object301. With this, the virtual camera 300 is turned clockwise by 90° aboutthe object 301 to be moved from the position A being the initial pointto the position B being the destination point, and the virtual camera300 is controlled to be directed toward the object 301. Along with thechange of the field of view region due to the turning movement of thevirtual camera 300, the image of the field of view to be displayed onthe display unit 112 is changed.

The movement of the virtual camera 300 is not limited to the turningmovement illustrated in FIG. 5, and may be parallel movement from theposition A to the position B as illustrated in FIG. 6. In this case, theposition to which the virtual camera 300 is moved is similar to that inthe case illustrated in FIG. 5, but the direction of the virtual camera300 is controlled to be the same between the position A and the positionB. That is, at the position B, the virtual camera 300 is not directedtoward the object 301.

In at least one embodiment, when the image of the field of view isupdated based on the movement of the virtual camera 300 arranged in thevirtual space 200, different methods are employed for updating the imageof the field of view between the case where the virtual camera 300 ismoved in synchronization with the movement of the HMD 110 and the casewhere the virtual camera 300 is moved without synchronization with themovement of the HMD 110. In the case where the virtual camera 300 ismoved in synchronization with the movement of the HMD 110, in atransition period of moving the virtual camera 300 from the position Ato the position B, the control circuit unit 120 generates a continuousimage of the field of view for a period in which the virtual camera 300is moved from the position A to the position B, and causes the displayunit 112 to display the continuous image of the field of view.Meanwhile, in the case where the virtual camera 300 is moved withoutsynchronization with the movement of the HMD 110, when the virtualcamera 300 is moved from the position A to the position B, the controlcircuit unit 120 generates a guiding region for attracting the sightline of the user together with the continuous image of the field of viewfor the period in which the virtual camera 300 is moved from theposition A to the position B, and causes the display unit 112 to displaythe guiding region for covering a part of the virtual space in the fieldof view.

FIG. 7 is a block diagram of hardware implemented functionality of thecontrol circuit unit 120, for achieving the processing of displaying thevirtual space 200, in particular, the processing of updating the imageof the field of view in the HMD system 100. The control circuit unit 120is configured to control an image to be output to the display unit 112based on the input from the HMD sensor 114, the movement sensor 130, andthe external controller 140.

As illustrated in FIG. 7, the control circuit unit 120 includes an imagegenerating unit 410, an input receiving unit 420, and a spaceinformation storing unit 430. The image generating unit 410 includes aspace image generating unit 411, a visual-field image generating unit412, an input determining unit 413, a first visual-field image updatingunit 414, and a second visual-field image updating unit 415.

FIG. 8 is a flow chart of a method of processing of updating the imageof the field of view according to at least one embodiment. FIG. 9 is adiagram of at least one example in which the guiding region is displayedon a part of the field of view. FIG. 10 is an illustration of anadditional configuration of the guiding region illustrated in FIG. 9.

As illustrated in FIG. 8, first, in the image generating unit 410, thespace image generating unit 411 refers to the space information storingunit 430, to thereby generate a virtual space image on a celestialsphere defining the virtual space 200 in which the user is immersed(Step S501). In the image generating unit 410, the unit 412 specifiesthe position and the direction of the virtual camera 300 at the initialpoint (for example, the position A of FIG. 5 or FIG. 6) of the virtualcamera 300 arranged in the virtual space 200, and specifies the image ofthe field of view that is visually recognizable by the user based on thespecified position and direction of the virtual camera 300 (Step S502).

Next, the input receiving unit 420 receives the input from the HMDsensor 114, the movement sensor 130, and the external controller 140 asinput for moving the position and/or the direction of the virtual camera300 from the initial point (Step S503).

Next, the unit 412 specifies a new position and a new direction of thevirtual camera 300 at the point (for example, the position B of FIG. 5or FIG. 6) where the virtual camera 300 should be located, based on theinput received by the input receiving unit 420. Then, the unit 412specifies a new image of the field of view at a destination point basedon the position and the direction of the virtual camera 300 at themoving destination (Step S504).

Depending on the content, in some cases, the virtual camera 300automatically moves in the virtual space independent of the movement ofthe HMD 110 or the input of the external controller 140. In those cases,Step S504 is executed by calculating the new position and the newdirection of the virtual camera at the moving destination independentlyof the input.

Next, the input determining unit 413 determines whether the virtualcamera 300 is moved in synchronization with the movement of the HMD 110(Step S505). That is, the input determining unit 413 determines whetherthe input in Step S503 is input from the HMD sensor 114 and/or themovement sensor 130 or input from the external controller 140.

When the input determining unit 413 determines that the input in StepS503 is input for moving the virtual camera 300 in synchronization withthe movement of the HMD 110 (that is, input from the HMD sensor 114and/or the movement sensor 130) (Step S505), the first visual-fieldimage updating unit 414 generates the image of the field of view to beupdated from the initial point specified in Step S502 to the destinationpoint specified in Step S504 (Step S506). Then, the first visual-fieldimage updating unit 414 outputs, to the HMD 110, information relating toa updating mode of the image of the field of view to be updated from theinitial point to the destination point as a result of executing StepS506. The HMD 110 receives this information to update the image of thefield of view to be displayed on the display unit 112 (Step S507). Whenthe visual field of the user is moved in the virtual space insynchronization with the movement of the HMD 110, VR motion sickness isless likely to result, and hence the image of the field of view to beupdated from the initial point to the destination point is able to bedisplayed on the display unit 112 without further modification.

On the other hand, when the input determining unit 413 determines inStep S505 that the input in Step S503 is input for moving the virtualcamera 300 without synchronization with the movement of the HMD 110(that is, input from the external controller 140), the secondvisual-field image updating unit 415 generates the guiding region forattracting the sight line of the user together with the image of thefield of view to be updated from the initial point specified in StepS502 to the destination point specified in Step S504 (Step S508). Then,the second visual-field image updating unit 415 outputs, to the HMD 110,information relating to a display mode of the sight line guiding regiontogether with information relating to a updating mode of the image ofthe field of view to be updated from the initial point to thedestination point as a result of executing Step S508. The HMD 110receives those pieces of information to cause the display unit 112 todisplay the guiding region so as to cover a part of the virtual space inthe field of view to be updated (Step S509).

FIG. 9 is at least one example of the image of the field of view and theguiding region that are displayed on the display unit of the HMD in StepS509.

The guiding region includes, for example, a blindfold object MO asillustrated in FIG. 9. The blindfold object MO is displayed so as tocover a part of an image of the field of view V to be continuouslyupdated. For example, the blindfold object MO is displayed as a bandportion at the center part of the image of the field of view V, but isnot displayed at upper and lower portions of the image of the field ofview V. The blindfold object MO attracts the sight line of the user. Forexample, an image (for example, a pattern) different from the image ofthe field of view V may be displayed. Examples of other configurationsof the blindfold object MO are given below.

Some character information (advertisement or others) is displayed as aband-shaped blindfold object, in at least one embodiment.

In at least one embodiment, only the center portion of the image of thefield of view is displayed, and the periphery excluding the centerportion is covered with the blindfold object.

In at least one embodiment, the center portion of the image of the fieldof view is displayed in an enlarged manner, and the periphery excludingthe center portion is covered with the blindfold object, to thereby givea visual effect as if the user is peering through a telescope.

In at least one embodiment, an image whose resolution or contrast isreduced as compared to that of the image of the field of view Vremaining as a background is displayed in, for example, a center part ofthe image of the field of view V.

As described above, when the image of the field of view V is updatedwithout synchronization with the movement of the HMD 110, the image ofthe field of view V and the blindfold object MO are displayed on thedisplay unit 112 of the HMD 110 such that the blindfold object MO coversa part of the virtual space in the field of view V. In this manner, anamount of information that is recognized by the brain of the user fromthe image of the field of view V (background image) being updated isreduced. Therefore, the user's VR motion sickness is reduced in someinstances. Further, the blindfold object MO is displayed so as not tocover the entire visual-field image V displayed on the display unit 112,but to cover a part of the field of view V. Therefore, the user canvisually recognize at least apart of virtual space in the image of thefield of view V subjected to update processing. Further, processing ofchanging the image of the field of view from a first-person perspectiveto a third-person perspective, e.g., processing of temporarily movingthe virtual camera to a higher-perspective position, which has beenperformed in the related art to reduce the VR motion sickness is reducedor avoided. Therefore, the user's sense of immersion to the virtualspace 200 maintained.

In at least one embodiment, the blindfold object MO is displayed so asto overlap with a part of the field of view particularly when thevirtual camera 300 is moved backward in the virtual space, when thevirtual camera 300 is moved at high speed, and when the virtual camera300 is moved in a curved motion. The reason is because the VR motionsickness is particularly liable to occur in the case of those movements.

Further, the blindfold object MO is preferably displayed so as to covera half or more of the field of view V displayed on the display unit 112.The blindfold object MO is further displayed so as to cover ⅔ or more ofthe field of view V. When the blindfold object MO is displayed large tosome extent, the visual effect of attracting the sight line of the usercan be sufficiently obtained, and thus the VR motion sickness can bereliably prevented or reduced.

Further, as illustrated in FIG. 10, the blindfold object MO is generatednot only in the field of view V defined as an image of the field of viewregion of the virtual camera 300 in the virtual space 200, but also tohave a size extending to a region outside of the field of view V. Forexample, the blindfold object MO may be generated to extend to a regionof about ±90 degrees about the reference sight line of the virtualcamera 300. With the extension of the blindfold object MO to the outsideof the region of the field of view V, even when the direction of thevirtual camera 300 is changed through movement of the head of the userduring update of the field of view without synchronization with themovement of the HMD 110 in Step S509 corresponding to the secondvisual-field image update step, the blindfold object MO can beappropriately displayed also in the field of view V that has changed insynchronization with the movement of the HMD 110. In at least oneembodiment, at least one object in the field of view V covered by theblindfold object MO is not rendered. Reducing a number of renderedobjects in the field of view V helps to reduce power consumption.

In Step S505 of FIG. 8, even when the input determining unit 413determines that the virtual camera 300 is moved without synchronizationwith the movement of the HMD 110, the blindfold object MO may not bedisplayed when the movement amount of the virtual camera 300 does notexceed a predetermined threshold. That is, the blindfold object MO maybe displayed only when the movement amount of the virtual camera 300exceeds the predetermined threshold. The reason is because, when themovement amount of the visual field is small, the VR motion sickness isless liable to occur even when the movement of the visual field out ofsynchronization with the movement of the HMD 110 is presented to theuser.

FIG. 11A to FIG. 11C are diagrams of at least one example of the imageof the field of view and the guiding region to be displayed on thedisplay unit 112 in Step S510 corresponding to a guiding region displaystep. FIG. 12 is a diagram of a configuration of the guiding regionaccording to the at least one example shown in FIG. 11A to FIG. 11C.

As shown in FIG. 11A to FIG. 11C, the guiding region may be formed of anobject (in this case, a robot character object R) on which the sightline of the user is attracted. The processing of updating the image ofthe field of view with use of this object (character object R) is asfollows.

When the input determining unit 413 determines that the input in StepS503 is input for moving the virtual camera 300 in synchronization withthe movement of the HMD 110, the first visual-field image updating unit414 updates the image of the field of view from the initial point to thedestination point, and outputs the information relating to the updatingmode of the image of the field of view to the HMD 110. The HMD 110 thathas received the information relating to the updating mode of the imageof the field of view updates the image of the field of view to bedisplayed on the display unit 112. In this case, the character object Ris not generated or displayed.

On the other hand, when the input determining unit 413 determines thatthe input in Step S503 is input for moving the virtual camera 300without synchronization with the movement of the HMD 110, the secondvisual-field image updating unit 415 generates the character object Rtogether with the image of the field of view to be updated from theinitial point specified in Step S502 to the destination point specifiedin Step S504. Then, the second visual-field image updating unit 415outputs, to the HMD 110, the information relating to the display mode ofthe image of the field of view to be updated from the initial point tothe destination point and the information relating to the updating modeof the character object R. The HMD 110 that has received the pieces ofinformation relating to the updating modes of the image of the field ofview and the character object R updates the image of the field of viewwhile displaying the character object R on the display unit 112 as shownin FIG. 11A to FIG. 11C.

Specifically, the character object R comes into the field of view V fromoutside of the field of view V (FIG. 11A), and moves to the centerportion of the field of view V (right in front of the user's eyes) (seeFIG. 11B). Then, the character object R performs such a motion as tomove the user from the initial point to the moving destination, and theimage of the field of view V is updated in accordance with this movementof the character object R (FIG. 11C). For example, when the virtualcamera 300 is moved forward, the image of the field of view is updatedfrom the initial point to the destination point in accordance with thecharacter object R performing a motion of pulling the user. Meanwhile,when the virtual camera 300 is moved backward, the image of the field ofview is updated from the initial point to the destination point inaccordance with the character object R performing such a motion as topush the user. Further, when only the direction of the virtual camera300 is changed (virtual camera is rotated), the image of the field ofview is updated from the initial point to the destination point inaccordance with the character object R performing such a motion as torotate the user.

As described above, the character object R being the object isconfigured to give, to the user, such a visual effect that the user ismoved in the virtual space 200 in a direction of change of the positionand/or the direction of the virtual camera 300. According to at leastone example, the user focuses his/her gaze on the moving characterobject R, and hence the amount of information that is recognized by thebrain of the user from the image of the field of view being updated isreduced. Further, with the above-mentioned motion of the characterobject R, such a visual effect that the user himself/herself having afirst-person perspective feels like being moved in the movementdirection of the virtual camera 300 can be given. Therefore, the user'spredictability for the update of the image of the field of view V isenhanced. Therefore, the user is less susceptible to the VR sickness.Further, the character object R is an object that does not cover theentire visual-field image V, but is displayed on a part of the image ofthe field of view V, and hence the user's sense of immersion to thevirtual space 200 is maintained.

Further, as illustrated in FIG. 12, preferably the character object R isable to be displayed (arranged) not only in the field of view V definedas the image of the field of view region 201 of the virtual camera 300in the virtual space 200, but also in a region outside of the field ofview V. For example, one character object R1 may be able to be displayedin the field of view region 201 of the user, while one character objectR2 and one character object R3 may be able to be displayed in a regionoutside of the field of view region 201 and in the vicinity of the fieldof view region 201. When the character objects R1 to R3 are able to bedisplayed not only in the image of the field of view V but also outsideof the region of the image of the field of view V, even when thedirection of the virtual camera 300 is changed through movement of thehead of the user during update of the image of the field of view withoutsynchronization with the movement of the HMD 110 in Step S509corresponding to the second visual-field image update step, thecharacter objects R2 and R3 can be appropriately displayed also in theimage of the field of view V that has changed in synchronization withthe movement of the HMD 110.

The above-mentioned embodiment are merely examples for facilitating anunderstanding of this disclosure, and does not serve to limit aninterpretation of this disclosure. One of ordinary skill in the artwould understand that this disclosure can be changed and modifiedwithout departing from the gist of this disclosure, and that thisdisclosure includes equivalents thereof.

What is claimed is:
 1. A method comprising: defining a virtual space forimmersing a user; defining a field of view of a head mounted display;generating an image of the field of view based on the virtual space thatis visually recognizable by the user; updating the image of the field ofview in synchronization with movement of the head mounted display;generating the image of the field of view including a guiding regionwhich covers a part of the virtual space for guiding a sight line of theuser when the image of the field of view is updated withoutsynchronization with the movement of the head mounted display; anddisplaying the image of the field of view on the head mounted display,wherein generating the image of the field of view comprises generatingthe guiding region covering at least half of the virtual space in thefield of view, wherein the at least half of the virtual space covered bythe guiding region is measured from a center of the field of view. 2.The method according to claim 1, wherein updating the image of the fieldof view comprises changing a position or a direction of a virtual cameradefining the field of view.
 3. The method according to claim 2, whereingenerating the image of the field of view comprises generating theguiding region comprising an object for attracting the sight line of theuser.
 4. The method according to claim 3, wherein generating the imageof the field of view comprises generating the object configured to givea visual effect of movement of the virtual camera in a direction ofchange of the position or the direction in the virtual space.
 5. Themethod according to claim 3, further comprising arranging the objectoutside of a region of the image of the field of view in the virtualspace.
 6. The method according to claim 2, wherein generating the imageof the field of view comprises generating the guiding region covering atleast half of the virtual space in the field of view.
 7. The methodaccording to claim 2, wherein generating the image of the field of viewcomprises generating the guiding region in the virtual space having asize extending to an outer edge of the image of the field of view. 8.The method according to claim 1, wherein generating the image of thefield of view comprises generating the guiding region in the virtualspace having a size extending to an outer edge of the image of the fieldof view.
 9. The method according to claim 1, wherein generating theimage of the field of view comprises generating the guiding region inthe virtual space having a size extending to an outer edge of the imageof the field of view.
 10. A system comprising: a non-transitory computerreadable medium configured to store instructions; and a processorconnected to the non-transitory computer readable medium, wherein theprocess is configured to execute the instructions to cause the systemto: define a virtual space for immersing a user; define a field of viewof a head mounted display; generate an image of the field of view basedon the virtual space that is visually recognizable by the user; updatethe image of the field of view in synchronization with movement of thehead mounted display; generate the image of the field of view includinga guiding region which covers a part of the virtual space for guiding asight line of the user when the image of the field of view is updatedwithout synchronization with the movement of the head mounted display;and display the image of the field of view on the head mounted display,wherein generating the image of the field of view comprises generatingthe guiding region covering at least half of the virtual space in thefield of view, wherein the at least half of the virtual space covered bythe guiding region is measured from a center of the field of view. 11.The system according to claim 10, wherein processor is configured toupdate the image of the field of view by changing a position or adirection of a virtual camera defining the field of view.
 12. The systemaccording to claim 11, wherein the processor is configured to generatethe guiding region comprising a sight line concentrating object on whichthe sight line is focused.
 13. The system according to claim 12, whereinthe sight line concentrating object is configured to give a visualeffect of movement in the virtual space in a direction of change of theposition or the direction of the virtual camera.
 14. The systemaccording to claim 12, wherein the processor is further configured toarrange the sight line concentrating object outside of a region of theimage of the field of view in the virtual space.
 15. The systemaccording to claim 11, wherein processor is configured to provideinstructions for displaying the guiding region so as to cover at leasthalf of the image of the field of view.
 16. The system according toclaim 11, wherein processor is configured to generate the guiding regionhaving a size extending to an outer edge of a region of the image of thefield of view in the virtual space.
 17. The system according to claim10, wherein processor is configured to generate the guiding regionhaving a size extending to an outer edge of a region of the image of thefield of view in the virtual space.
 18. The system according to claim10, wherein processor is configured to generate the guiding regionhaving a size extending to an outer edge of a region of the image of thefield of view in the virtual space.